Note: This document is for an older version of GRASS GIS that is outdated. You should upgrade, and read the current manual page.

NAME

KEYWORDS

SYNOPSIS

Flags:

-p

Create VTK pointdata instead of VTK celldata (celldata is default)

-s

Create 3d elevation output with a top and a bottom surface, both raster maps are required.

-m

Use 3D raster mask (if exists) with input maps

-o

Scale factor effects the origin

-c

Correct the coordinates to fit the VTK-OpenGL precision

--verbose

Verbose module output

--quiet

Quiet module output

Parameters:

input=name[,name,...]

G3D map(s) to be converted to VTK-ASCII data format

output=name

Name for VTK-ASCII output file

null=float

Float value to represent no data cell/points

Default: -99999.99

top=string

top surface 2D raster map

bottom=string

bottom surface 2D raster map

rgbmaps=string[,string,...]

Three (R,G,B) 3D raster maps to create RGB values [redmap,greenmap,bluemap]

vectormaps=string[,string,...]

Three (x,y,z) 3D raster maps to create vector values [xmap,ymap,zmap]

elevscale=float

Scale factor for elevation

Default: 1.0

dp=integer

Number of significant digits (floating point only)

Options: 0-20

Default: 12

DESCRIPTION

NOTES

The top and bottom region values are expected in meters. If a Latitude-Longitude (LL) coordinates are used, the elevation value for each voxel will be converted into degrees.

The input, rgbmaps and vectormaps parameters are optional, so only the geometry can be exported.

If the user defines top and bottom and the 2D and 3D region values differ, the 2D resolution will be adjusted to the 3D resolution. The elevation maps are expected in meters. If Lat/Long coordinates are used, the elevation will automatically converted into degree. If the surface and bottom maps are in a different unit than meters, use the scale parameter to convert them into meters.

The RGB voxel data can be created from 2D raster maps (Landsat TM images) with r.to.rast3. The values of the RGB maps must be within 0 and 255. If not, the values are automatically set to 0 and warnings will be printed to stderr.

The vector data is created from three 3D raster maps. Each map represents a vector component. So x, y and z components are required in this order. This data can be visualized with Glyph3d or StreamTracer filters within Paraview.

If the -c flag is used and the data should be visualised together with other data exported via *.out.vtk modules, be sure the -c flag was also set in these modules. But this will only work with data from the SAME location (the reference point for the coordinates transformation is based on the center point of the default region).

Difference between point- and celldata

• pointdata -- the cells/values are represented by the center of the cell. Instead of cells, points are created. Each point can hold different values, but the user can only visualize one value at a time.
• celldata The cells are created with the same hight, width and depth as in GRASS. Each cell can hold different values, but the user can only visualize one value at a time.

EXAMPLE

Simple Spearfish example

g.region -d
g.region res=150 res3=150 t=80 b=0 tbres=10
r.mapcalc "bottom = 1800. - elevation.10m"

# synthetic data, could be geological structures:
r3.mapcalc "map3d = row()+col()+depth()"

#export of volume to VTK:
r3.out.vtk -s input=map3d top=elevation.10m bottom=bottom output=/tmp/out.vtk

# visualize in paraview or other VTK viewer:
paraview --data=/tmp/out.vtk

Spearfish example with RGB data

#set the region
g.region -d
g.region n=4926970 s=4914857 w=591583 e=607793 res=50 res3=50 t=80 b=0 tbres=10

#create a bottom surface
r.mapcalc "bottom = 1800. - elevation.10m"

# synthetic data, could be geological structures:
r3.mapcalc "map3d = row()+col()+depth()"

#get some satellite images with r.in.onearth
r.in.onearth -l output=Sat tmband=Red
r.in.onearth -l output=Sat tmband=IR1
r.in.onearth -l output=Sat tmband=IR2

#Convert the 2d maps to 3d raster maps with r.to.rast3
r.to.rast3 input=SatLandsatTM_Red output=SatLandsatTM_Red
r.to.rast3 input=SatLandsatTM_IR1 output=SatLandsatTM_IR1
r.to.rast3 input=SatLandsatTM_IR2 output=SatLandsatTM_IR2

#export of volume to VTK:
r3.out.vtk -s rgbmaps=SatLandsatTM_IR1,SatLandsatTM_IR2,SatLandsatTM_Red
input=map3d top=elevation.10m bottom=bottom output=/tmp/out.vtk

# visualize in paraview or other VTK viewer:
paraview --data=/tmp/out.vtk 

Spearfish example with vector data

# set the region
g.region -d
g.region n=4926970 s=4914857 w=591583 e=607793 res=50 res3=50 t=80 b=0 tbres=10

# create a bottom surface
r.mapcalc "bottom = 1800. - elevation.10m"

# synthetic data, could be geological structures:
r3.mapcalc "map3d = row()+col()+depth()"

# synthetic vector data, could be groundwater stream vectors
r3.mapcalc "x_part = sin(row())"
r3.mapcalc "y_part = cos(col())"
r3.mapcalc "z_part = sin(depth())"


# export the stuff data to VTK:
r3.out.vtk -s vectormaps=x_part,y_part,z_part input=map3d top=elevation.10m
bottom=bottom output=/tmp/out.vtk

# visualize in paraview or other VTK viewer:
paraview --data=/tmp/out.vtk 
# Now use the Glyph and Stream-Trace Filter to get nice vectors and streamlines

Slovakia3d example

#reduce resolution:
g.region -dp3 res=1000 res3=1000
r.mapcalc "bottom = 100"

#export of volume to VTK:
r3.out.vtk -s in=precip3d.500z50 top=dem500 bottom=bottom
out=/tmp/slovakia3d.vtk

# visualize in paraview or other VTK viewer:
paraview --data=/tmp/slovakia3d.vtk
# set Display style to 'surface#
# set Actor Control z to 10

SEE ALSO

AUTHOR

Last changed: $Date: 2011-09-13 13:14:59 -0700 (Tue, 13 Sep 2011) $

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